Light emitting diodes (LEDs) are becoming an increasingly popular source of light in a number of lighting applications. In many of these applications, LEDs may serve as an improvement over the previously used incandescent or fluorescent lamps because of the low voltage and high efficiency at which LEDs operate. Unfortunately, when one or more LEDS are coupled to a lighting cavity (such as a backlighting cavity) in order to mix and redirect light, optical losses may occur due to multiple reflections within the cavity which do not escape. Further, it is often a challenge to sample optical output of an optical cavity without degrading optical output. It would therefore be highly desirable to provide a solution to optical losses in the cavity while also sampling the light for appropriate characteristics without degrading optical output.